The objectives of the work outlined in this research proposal are 1) to determine the precise role of the lymphatic vascular system in the maintenance of fluid homeostasis in normal conditions and 2) to examine those morphological and physiological events which occur during the inflammatory response. In determining the fate of small and large molecules on their journey from plasma to lymph, special attention will be given to investigating the transport of proteins and fluids across the blood-tissue-lymph interface. In addition, the mechanisms involved in the unidirectional flow of lymph from the lymphatic capillaries to the larger collecting vessels will be studied. In order to obtain additional information regarding the chemical and structural events which are involved in tissue defense mechanisms, an investigation of lymph nodes prior to, and after antigenic stimulations, will also be undertaken. These studies will be carried out using histological, cytochemical, and biochemical techniques and will include ultrastructural examinations using freeze-etching, transmission, and scanning electron microscopy and cinephotographic methods.